1. Field of the Invention
The invention is directed to a traveling gear or running mechanism, and in particular a running mechanism for chain hoists, load carrying means or trailing cable.
2. Description of the Related Art
A running mechanism with two frames arranged so as to be swivelable with respect to one another and with rotatably mounted running rollers which are supported by the flange parts and the web of the running rail is disclosed in German patent publication 494 451. The running rollers substantially run in channels, i.e., in the round transitional regions between flange and web which guide the running mechanism. Thus, the running rollers accomplish the twofold task of carrying and guiding the running mechanism with the load. The frames are connected with one another in an articulated manner by a transverse support by a pin at one end of the transverse support. The distance between these swivel pins is selected so that the running wheels run in the channels of the rails without problems. In order to improve the guidance of the running mechanism, a guide roller is provided underneath the rail which rolls along the outer side of the lower flange of the rail and comes into contact with it under the influence of applied force. One side of the swivel pin of the guide roller is connected to a gear unit to drive the running mechanism. The guide roller performs two functions, a driving function and a guiding function. A disadvantage of this known running mechanism is that the running rollers and the driving roller simultaneously used to guide the running mechanism require a specially designed running mechanism construction which is relatively expensive to assemble and which requires a rail adapted to the running mechanism for trouble-free running.
German patent publication 41 09 971 A1 discloses a running mechanism with running wheels on both sides of an I-shaped running rail contacted on one side by front and rear lateral guide rollers which are mounted on vertical axles. This running mechanism also travels on the support rail in a stable manner in the case of loads swinging in a pendulum-like manner. Nevertheless, the running stability of this running mechanism is limited, in that during critical situations the running mechanism has a tendency to pitch and rock in a pendulum-like manner. Moreover, the running mechanism has a relatively complex construction, is expensive to manufacture and is difficult to mount on the support.
Another running mechanism is disclosed in German patent publication 42 09 565 A1 as including a crane trolley with a lifting mechanism of compact overall height having running wheels which run on the lower flange of a rail and are supported by a supporting frame part. One of the running wheels of this lower flange crane trolley is driven and supported by a rocker which is arranged on the supporting frame part so as to be swivelable. A friction wheel is arranged on the rocker which contacts the lower flange of the rocker from below and is in a driving connection with the driven running wheel. An adjustable eccentric ensures uniform contact of all running wheels at the lower flange. This crane trolley is advantageous for situations in which extensive reinforcement by frictional engagement is required; however, it is disadvantageous in that it requires a relatively high assembly cost for mounting the crane trolley on the support and is not suitable for use with different web thicknesses and flange widths.
Another crane trolley with at least one running wheel is disclosed in German patent publication 30 30 929 A1. This crane trolley is provided with laterally arranged guide rollers which contact vertical guide surfaces of a rail carrier arranged one above the other. The upper guide rollers together with the lower guide rollers effectively prevent a tilting of the crane trolley at the rail carrier, and the front guide rollers together with the rear guide rollers ensure defect-free guiding of the crane trolley in the longitudinal direction of the rail carrier. This crane trolley is disadvantageous in that it is relatively expensive to mount on the support despite the small number of individual parts. In addition, the relatively small intermediate space, approximately 1 mm, between the guide surfaces and the guide rollers does not provide adequate compensation for tolerances so as to ensure trouble-free parallel running of the running rollers.
Thus, it is desirable to provide a running mechanism which is capable of automatically adapting to different web thicknesses yet be readily assembled and not have a tendency to rock from side-to-side even when the load swings in a pendulum-like manner.